Safety device for the control elements of a manually operated soil compaction roller

ABSTRACT

The invention relates to a safety device for the manually operated soil compaction roller, comprising an operating lever and an adjusting element coupled to an actuator in order to drive said roller. In case of danger, a safety-control element travels in between the adjusting element and the operating lever and separates the positive coupling, whereupon the adjusting element swings into a neutral position and shuts down the machine. When the operating lever swings forwards, a command corresponding to a forward movement is transmitted to the drive mechanism of said roller via a second positive coupling.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a safety arrangement for a manually guided soilcompaction roller.

2. Description of the Related Art

In such soil compaction rollers, in particular rollers which are runwith an operator in attendance, the operator walks behind the roller andcontrols it via a handle, which is fastened to a pole and has a travellever for setting the travel speed and direction. The roller is normallymoved via a hydraulic unit in forward direction and reverse direction,that is toward the operator.

A safety arrangement, often also referred to as dead man's circuit,serves in such soil compaction rollers to switch off the propulsion ofthe roller if the roller moves backward, i.e. in the direction of theoperator guiding the roller, and the operator himself can no longer movebackward or cannot escape from the roller. This problem may occur, forexample, if the operator walks backward with the roller into anobstacle, gets into a panic and consequently forgets to stop the rolleror move it in the opposite direction.

An actuator which is able to register the fact that the roller runsagainst an obstacle, for example the operator, is therefore provided inknown safety arrangements. To this end, the safety arrangements have anactuator which is displaceable between an operating position and ahazard position and, if the operator comes into contact with it, isdisplaceable out of the operating position into the hazard position andconsequently stops the roller.

To this end, it is stipulated in standards that, after the response ofthe safety device, the stopping travel of the roller must be smallerthan the remaining operating travel of the actuator after the roller isswitched off in order to avoid squeezing the operator.

DE-A 41 29 915 A1 discloses a safety arrangement in which the travelspeed and direction can be set via a travel lever. The roller is guidedvia an additional handle, which is vertically pivotable like a lever andcan be pivoted from an upswung basic position down into a workingposition in which its free end is still clearly above the horizontalestablished by its pivot. The travel lever, otherwise held in neutralposition by spring loading, is fixed in the desired deflected positionin a positive-locking manner by swinging down the handle. When thehandle is swung up, which is effected automatically, for example, if thehandle comes into contact with an obstacle, the positive-lockingconnection is neutralized, as a result of which the travel lever movesinto the neutral position in a spring-loaded manner and stops theroller. Movement of the roller in the opposite direction is possible byfurther actuation of the travel lever.

In such solutions, it is always possible to reach the neutral positionor set the forward direction by actuation of the travel lever. In thiscase, it was assumed that the operator, upon coming into contact with anobstacle at the rear, releases the travel lever or that the holdingforce of the operator is less than the restoring force, initiated by thesafety actuator, on the travel lever. However, it has been found thatthe holding force of the hand, in particular in a panic situation, canbecome enormous, so that the operator does not let go of the travellever and, by further travel of the roller, a permitted maximum force of230 newtons may be exceeded by the safety actuator in contact with thebody of the operator. However, a higher loading than the admissiblemaximum force may alone result in considerable injuries to the operator.

In order to remove this problem, solutions in which, despite the forcewith which the operator takes a firm hold of the travel lever, apositive-locking connection between travel lever and the control lineleading to the drive is unlocked by the safety actuator detecting theobstacle have been proposed. As a result, the spring-loaded control linejumps into the stop position. A disadvantage of this principle, however,is that the positive-locking connection between travel lever and controlline can only be restored when the safety actuator displaced by theobstacle has again reached its initial or operating position, so that acoupling between travel lever and control line becomes possible again.Not until then is a movement of the roller in the opposite directionpossible. To this end, however, the operator must have freed himselffrom his jammed position beforehand, since otherwise the safety actuatorcannot be returned into the operating position.

OBJECTS AND SUMMARY OF THE INVENTION

The object of the invention is to specify a safety arrangement for amanually guided soil compaction roller, which safety arrangement, evenif the operator frantically keeps a firm hold of the travel lever,permits reliable stopping of the roller and, on the other hand, permitsforward travel of the roller away from the operator even if the safetyarrangement has been triggered by travel of the roller against theoperator.

According to the invention, the object is achieved by a safetyarrangement having the features of patent claim 1. Advantageousdevelopments of the invention can be gathered from the dependent claims.

In the safety arrangement according to the invention, in addition to thefirst coupling known per se, often designed as a jaw clutch, between atravel lever and an adjusting element connected to a control line, asecond coupling is provided. The first coupling can be released bydisplacement of a safety actuator from an operating position into ahazard position. The second coupling, however, is retained even in thiscase, but can only transmit forces of the travel lever to the adjustingelement if the travel lever is moved in the forward direction. This hasthe advantage that, if the roller runs into an obstacle and the safetyactuator is actuated by the obstacle, e.g. the body of the operator, thefirst coupling is neutralized, as a result of which the adjustingelement moves into neutral position in a spring-loaded manner and stopsthe roller. So that the operator can free himself from his emergencysituation, he can put the travel lever, which at first is still in thereverse travel position, into the forward position. The movement of thetravel lever in the forward direction is transmitted via the secondcoupling to the adjusting element and thus via the control line to thedrive of the roller, so that the latter moves in the forward directionaway from the operator and releases the latter.

The second coupling likewise preferably has a positive-locking clutch inwhich the adjusting element carries a driver, against which a stopprovided on the travel lever can run. This ensures that forces can betransmitted only in one direction, namely the forward direction of theroller.

BRIEF DESCRIPTION OF THE DRAWINGS

These and further advantages and features of the invention are explainedin more detail below with the aid of the attached figures, in which:

FIG. 1 shows a perspective view of a handle for a soil compaction rollerwith the safety arrangement according to the invention in the operatingposition;

FIG. 2 shows the handle from FIG. 1 with the safety arrangement inhazard position;

FIG. 3 shows a front view of the safety arrangement according to theinvention in accordance with the position of FIG. 1;

FIG. 4 shows a front view of the safety arrangement in accordance withthe position of FIG. 2:

FIG. 5 shows a side view of the handle with the safety arrangementaccording to the invention and a travel lever in forward position;

FIG. 6 shows a side view of FIG. 1 with the travel lever in reverseposition;

FIG. 7 shows a side view of FIG. 2 with travel lever in reverse positionand safety actuator in hazard position;

FIG. 8 shows a side view of the handle with travel lever in forwardposition and safety actuator in hazard position.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The figures essentially show the same arrangement, but with differentpositioning of the elements. Therefore the construction of the safetyarrangement according to the invention will first of all be describedwith reference to FIGS. 1 and 3. A description of the mode of operationthen follows with reference to the further figures.

A handle 2 is fastened to a retaining plate 1 fastened to a pole (notshown) of a soil compaction roller, via which handle 2 the soilcompaction roller can be guided in a conventional manner. In the arch ofthe handle 2, a travel lever 3 is arranged so as to be pivotable on apivot 4. For ergonomical reasons, the travel lever 3 has an extension 5,which is designed in such a way that it can be grasped by the operatorat the same time as the operator keeps a firm hold of the handle 2. Thetravel lever 3 is pivotable in the forward or reverse direction, a factwhich is identified by arrows V and R.

The movement of the travel lever 3 can be transmitted to an adjustingelement 7 via a jaw clutch 6, which can be seen in particular in FIG. 3and serves as first coupling. The adjusting element 7 is likewisearranged so as to be pivotable on the pivot 4 and is pivotably coupledat one lever end 8 to the end of an actuating device 9 serving ascontrol line. A drive (not shown) for the roller can be activated viathe actuating device 9, which is designed, for example, as a Bowdencable. The drive is normally a hydraulic pump, the pumping capacity ofwhich can be adjusted by means of the actuating device 9. Instead of aBowden cable, a control linkage, for example, may also be used for theactuating device 9.

The adjusting device 7 is provided on one side with the jaw clutch 6 andis loaded on the other side by a spring 10, which is supported against astep 11 on the pivot 4.

As a result, the jaw clutch 6 is kept closed by spring loading, and themanual force, acting on the travel lever 3, of the operator istransmitted in a positive manner to the adjusting element 7 and theactuating device 9.

Furthermore, a safety actuator, which essentially comprises an impactpot 12, a plunger 13 and a guide 14, is arranged on the retaining plate1. The impact pot 12 is firmly connected to the plunger 13 and, by meansof a spring 15 supported against the guide 14, is held in an operatingposition, in which the control is not affected by the safety actuator.However, the plunger 13 is held in the guide 14 in an axially movablemanner, so that the plunger 13 can be displaced with the impact pot 12out of the operating position into a hazard position against the actionof the spring 15 if the impact pot 12 runs, for example, into the bodyof the operator or another obstacle.

The hazard position is shown in FIG. 2. In this case, it can be seenthat the impact pot 12 with the plunger 13 has been displaced in theforward direction V of the roller, i.e. in the direction of the jawclutch 6. By the penetration of a conical point 16, formed on theplunger 13, between the two halves of the jaw clutch 6, i.e. between theadjusting element 7 and the travel lever 3, the adjusting element 7 isdisplaced axially against the action of the spring 10, whereupon the jawclutch 6 is disengaged. As a result, the force flow between the travellever 3 and the adjusting element 7 is neutralized. The adjustingelement 7 is loaded by a spring device (not shown) in such a way that,when it is not loaded by the travel lever 3, it pivots automaticallyinto neutral position, which corresonds to a stoppage of the roller. Ifthe jaw clutch 6 is therefore disengaged, the adjusting element 7automatically pivots into its neutral position and stops the travel ofthe roller via the actuating device 9. The disengaged clutch 6 is alsoshown in FIG. 4, from which it can clearly be seen that the plunger 13lifts the adjusting element 7 from the travel lever 3.

However, the problem that the operator may already be jammed between theimpact pot 12 and an obstacle is still not solved with the stoppage ofthe roller. In order to free himself, the operator, according to theinvention, can therefore pivot the travel lever 3 in forward directionV. When the neutral position of the adjusting element 7 is reached, apositive-locking clutch serving as second coupling comes intoengagement, this positive-locking clutch being formed by a pin 17fastened to the travel lever 3 and a driver 18 formed on the adjustingelement 7. The pin 17 extending in the axial direction of the pivot 4 isso long that it can reach the driver 18 even if the adjusting element 7is disengaged by the plunger 13.

During forward movement of the travel lever 3, the pin 17 thereforepresses against the surface of the driver 18 and pivots the adjustingelement 7 in the forward direction. The movement of the adjustingelement 7 is accordingly transmitted via the actuating device 9 to thedrive of the roller, as a result of which the roller moves away from thejammed-in operator in the forward direction.

Instead of the arrangement of the second coupling shown in FIG. 1, it isof course also possible for the adjusting element 7 to carry a pin,against which the travel lever 3 runs during forward movement. In normaloperation, it is in addition expedient for no contact to take placebetween the pin 17 and the driver 18 when the jaw clutch 6 is engaged.Instead of a pin 17 inserted into the travel lever 3 as shown in FIGS. 3and 4, another stop may of course also be formed on the travel lever 3.

For better understanding, the abovedescribed mode of operation of thesafety arrangement is explained below with reference to the side viewsshown in FIGS. 5 to 8.

FIG. 5 shows the travel lever 3 in the forward position and the safetyactuator with the impact pot 12 in the operating position. Accordingly,FIG. 6 shows the travel lever 3 in reverse position. The position of thetravel lever 3 is transmitted via the respectively engaged jaw clutch 6to the adjusting element 7 and the actuating device 9, so that areliable control of the roller drive is possible.

FIG. 7 shows a state in which the roller was first of all in reversetravel due to the travel lever 3 located in reverse position and then anobstacle was detected via the impact pot 12. The plunger 13 has beenpushed against the jaw clutch 6 and has released the latter.Accordingly, the spring-preloaded adjusting element 7 has pivoted intoneutral position and stopped the drive via the actuating device 9. Themachine is stopped in the state shown in FIG. 7.

In the state shown in FIG. 8, the operator has pivoted the travel lever3 in the forward direction V, so that the pin 17 has been able to runagainst the driver 18 of the adjusting element 7. By further movement ofthe travel lever 3 in forward direction V, the appropriate controlcommand is transmitted via the actuating device 9 to the drive of theroller and the latter is driven in forward direction. By moving theroller away from the body of the operator, the impact pot 12 can returninto its original operating position, whereupon the plunger 13 isdisplaced out of the jaw clutch 6 and the jaw clutch 6 can engage again.The original operating state is thus restored.

Apart from being used in rollers, the safety arrangement may of coursealso be used in other machines which are run with an operator inattendance.

What is claimed is:
 1. A safety arrangement for a manually operated soilcompaction roller, having a travel lever (3) determining the traveldirection and speed and movable forward (V) and backward (R) as viewedin the travel direction of the roller; an adjusting element (7) coupledto the travel lever (3) via a first coupling (6) and intended fortransmitting the travel-lever position to an actuating device (9), theadjusting element (7), when not loaded by the travel lever (3), beingpreloaded in a center position corresponding to zero travel speed; asafety actuator (12, 13) which is arranged so as to be movable betweenan operating position and a hazard position and is preloaded in theoperating position and by means of which the first coupling (6) isseparable in the hazard position; and a second coupling (17, 18) oftravel lever (3) and adjusting element (7), by means of which, when thefirst coupling (6) is separated, forces can be transmitted only duringforward movement of the travel lever (3).
 2. The safety arrangement asclaimed in claim 1, wherein the first and/or the second coupling has apositive-locking clutch.
 3. The safety arrangement as claimed in claim2, wherein the first coupling has a jaw clutch (6).
 4. The safetyarrangement as claimed in claim 3, wherein the adjusting element (7) isaxially displaceable on a pivot (4) of the travel lever (3) against theaction of a spring (10).
 5. The safety arrangement as claimed in claim4, wherein the adjusting element (7) is axially displaceable by thesafety actuator (12, 13) in such a way that the jaw clutch (6)disengages if the safety actuator (12, 13) reaches its hazard position.6. The safety arrangement as claimed in claim 1, wherein the secondcoupling has a driver (18) on the adjusting element (7), against whichdriver (18) a stop (17) provided on the travel lever (3) can run.
 7. Thesafety arrangement as claimed in claim 6, wherein the stop is a pin(17), which is fastened to the travel lever (3) and extends parallel tothe pivot (4)